Seroprevalence of SARS-CoV-2 neutralizing antibodies among travelers entering Ghana through major land borders, pre- and post-opening of borders, 2022

Sero-epidemiological surveillance of SARS-CoV-2 in Africa has been pivotal in informing evidence-based pandemic response and border control strategies. To mitigate viral transmission, Ghana initially closed its air and land borders but later reopened them under regulated conditions. This study evaluated the seroprevalence of SARS-CoV-2 neutralizing antibodies among travelers entering Ghana via major land borders pre- and post-opening. Using a cross-sectional study design, individuals aged 18 years and above who entered Ghana through one of the ten major land borders from February to July 2022 were recruited consecutively after providing informed consent. During enrolment, participants completed a semi-structured questionnaire to gather data on background characteristics, vaccination status, travel history, and symptoms. Blood samples were collected and analyzed using the WANTAI ELISA to detect SARS-CoV-2 neutralizing antibodies. Separate logistic regression models were fitted for the pre-border and post-border periods, and the Benjamini-Hochberg procedure was used to control the false discovery rate across all non-reference adjusted coefficient tests within each model. The overall seroprevalence of SARS-CoV-2 neutralizing antibodies was 92.3% (95% CI: 91.4–93.0). Seroprevalence was higher before border reopening (95.7%; 95% CI: 94.2–97.1) than after reopening (91.6%; 95% CI: 91.0-92.5). After false discovery rate correction, travelers entering through Oseikojokrom and Akanu had lower odds of seropositivity before reopening, while those entering through Oseikojokrom, Akanu, Elubo, Paga, and Sampa had lower odds after reopening, compared with Aflao (q < 0.05). Vaccinated travelers had 2.5 times higher odds of seropositivity before reopening (aOR = 2.5, 95% CI: 1.7–3.5, q < 0.001) and 1.8 times higher odds after reopening (aOR = 1.8, 95% CI: 1.3–2.6, q = 0.005). The persistently high seroprevalence of SARS-CoV-2 neutralizing antibodies pre- and post-border reopening suggests that Ghana posed little to no risk of cross-border transmission. The study’s findings from the pre-border-opening assessment provided evidence to inform recommendations for reopening Ghana’s land borders, emphasizing the importance of strong border surveillance to prevent the importation and spread of pathogens.